A major part of our work has been studying the cellular basis somatosensory coding. We have concentrated on small subsets of trigeminal and dorsal root ganglion neurons expressing TRP-ion channels and have used a variety of screening techniques to explore the molecular architecture of these neurons. In this reporting period we identified,characterized and reported our findings on the neuropeptide Nppb. We discovered that Nppb is a primary transmitter of itch sensation. This peptide is released at the periphery and activates a central itch pathway that is selectively tuned. Additional experiments demonstrated a second neuropeptide, GRP, is downstream of Nppb. In a different set of studies, we examined the sensory cells required for mammalian thermosensation. Our work demonstrates that TRPV1- and TRPM8-expressing cells are hot and cold receptor neurons respectively. Furthermore, we established that afferent input from these cells combines to generate the sensation of warmth. Lastly, we found that a third separate population of neurons defined by the expression MrgD are responsible for responses to noxious temperatures.

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National Institute of Dental & Craniofacial Research
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Pandey, Mritunjay; Zhang, Jian-Hua; Mishra, Santosh K et al. (2017) A central role for R7bp in the regulation of itch sensation. Pain 158:931-944
Ran, Chen; Hoon, Mark A; Chen, Xiaoke (2016) The coding of cutaneous temperature in the spinal cord. Nat Neurosci 19:1201-9
Hoon, Mark A (2015) Molecular dissection of itch. Curr Opin Neurobiol 34:61-6
Mishra, Santosh K; Hoon, Mark A (2015) Transmission of pruriceptive signals. Handb Exp Pharmacol 226:151-62
Goswami, Samridhi C; Mishra, Santosh K; Maric, Dragan et al. (2014) Molecular signatures of mouse TRPV1-lineage neurons revealed by RNA-Seq transcriptome analysis. J Pain 15:1338-1359
Tränkner, Dimitri; Hahne, Nadeau; Sugino, Ken et al. (2014) Population of sensory neurons essential for asthmatic hyperreactivity of inflamed airways. Proc Natl Acad Sci U S A 111:11515-20
Bautista, Diana M; Wilson, Sarah R; Hoon, Mark A (2014) Why we scratch an itch: the molecules, cells and circuits of itch. Nat Neurosci 17:175-82
Goswami, Samridhi C; Thierry-Mieg, Danielle; Thierry-Mieg, Jean et al. (2014) Itch-associated peptides: RNA-Seq and bioinformatic analysis of natriuretic precursor peptide B and gastrin releasing peptide in dorsal root and trigeminal ganglia, and the spinal cord. Mol Pain 10:44
Mishra, Santosh K; Hoon, Mark A (2013) The cells and circuitry for itch responses in mice. Science 340:968-71
Pogorzala, Leah A; Mishra, Santosh K; Hoon, Mark A (2013) The cellular code for mammalian thermosensation. J Neurosci 33:5533-41

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